1. Field of the Invention
The present invention relates generally to the field of multimedia communication, and specifically, to a system and apparatus to provide a back-channel for receiver terminals in a conference.
2. Description of Related Art
Recommendation H.323, entitled "Visual Telephone Systems and Equipment for Local Area Networks Which Provide a Non-guaranteed Quality of Service", (version 1, published November 1996), describes terminals, equipment, and services for multimedia communication over local area networks ("LANs") and wide area networks ("WANs"). In particular, terminals compatible with Recommendation H.323 ("H.323 terminals") carry real-time voice, data, video, or any combination thereof including video telephony over a network (e.g., Internet). However, H.323 is limited in scalability due to the requirements for tightly-coupled conferencing. That is, H.323 requires that all participants in a conference be known in addition to a set of procedures for conference setup, capability negotiation, creation and control of audio/video/data streams, and conference tear down, all of which account for overhead. A central multipoint controller ("MC") is used for such procedures. Such a procedure for conference setup and capability negotiation at the start of the conference, though essential for tightly-coupled conferences, is cumbersome and impractical for conferences involving an arbitrarily large number of participants.
It is desirable to have a mechanism that allows a group of participants to work in an orderly manner, regardless of the size of the group such that the interaction among participants is not affected as the group scales to hundreds and/or thousands of participants. One method used to solve this problem is to assume that social (human) control will automatically force participants to work cooperatively regardless of the size of the group. However, the problem with this solution is that social control works best in a small group and when everyone in a group can see each other. Even in a large auditorium with hundreds of people, all the participants can see each other and can possibly work cooperatively. But in video conferencing, where it is not possible to see hundreds of participants, social control does not work well.
A second method used to solve the problem is to provide an automatic floor-control mechanism where one participant is in charge of allowing one or more participants to speak at any one time. However, the problem with this method is that since it is centralized, it does not scale well to an arbitrary large number of participants.
Accordingly, there is a need in the art for a method and apparatus to provide a back-channel for a receiver terminal in a loosely-coupled conference potentially involving hundreds and/or thousands of participants.